Cryosurgery is a surgical technique that employs freezing to destroy undesirable tissue. From as early as 3500 BC, there is evidence for the use of cold in medicine for the treatment of infected wounds of the chest, fracture of the skull and various injuries. However, the history of modern cryosurgery is relatively short and is closely intertwined with the development in low temperature physics, engineering, and instrumentation during the last century. From the early 21st century, advanced helium-based cryosurgery has been applied worldwide. More than ten thousand patients with malignant and benign tumors have received cryosurgery. It is specially noted that in most cases cryosurgery, as a mini-invasive ablation technique, was performed with percutaneous approach under guidance of CT or ultrasound. Cryosurgery is now one of the more popular techniques in China, with nearly 6000 cases of tumors receiving cryosurgery in the author's institution alone. This book summarizes the experimental and clinical experience and practice of cryosurgery, and describes the basics of cryosurgery and its use in the treatment of various tumors.